<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width,minimum-scale=1.0,maximum-scale=1.0"/>
  <title>Grid Layout</title>
  <link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
  <div class="row">
    <div class="col-gt768-4 col-lt768-6">
      <div class="block"></div>
    </div>
    <div class="col-gt768-4 col-lt768-6">
      <div class="block"></div>
    </div>
    <div class="col-gt768-4 col-lt768-12">
      <div class="block"></div>
    </div>
  </div>

  <div class="row">
    <div class="col-gt768-3 col-lt768-3">
      <div class="block"></div>
    </div>
    <div class="col-gt768-6 col-lt768-6">
      <div class="block"></div>
    </div>
    <div class="col-gt768-3 col-lt768-3">
      <div class="block"></div>
    </div>
  </div>

  <div class="row">
    <div class="col-gt768-1 col-lt768-2">
      <div class="block"></div>
    </div>
    <div class="col-gt768-1 col-lt768-2">
      <div class="block"></div>
    </div>
    <div class="col-gt768-2 col-lt768-8">
      <div class="block"></div>
    </div>
    <div class="col-gt768-2 col-lt768-3">
      <div class="block"></div>
    </div>
    <div class="col-gt768-6 col-lt768-3">
      <div class="block"></div>
    </div>
  </div>
</body>
</html>